US10439530B2 - Motor controller - Google Patents

Motor controller Download PDF

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US10439530B2
US10439530B2 US16/176,288 US201816176288A US10439530B2 US 10439530 B2 US10439530 B2 US 10439530B2 US 201816176288 A US201816176288 A US 201816176288A US 10439530 B2 US10439530 B2 US 10439530B2
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phase
current
stator
compensation
currents
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US20190149072A1 (en
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Ryo Suzuki
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Denso Corp
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Denso Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/28—Arrangements for controlling current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/08—Arrangements for controlling the speed or torque of a single motor
    • H02P6/085—Arrangements for controlling the speed or torque of a single motor in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2209/00—Indexing scheme relating to controlling arrangements characterised by the waveform of the supplied voltage or current
    • H02P2209/01—Motors with neutral point connected to the power supply

Definitions

  • the present disclosure generally relates to a motor control technique for controlling a three-phase motor that is driven by a three-phase electric current.
  • Brushless motors may include two stators with each stator being driven from a three-phase alternating current (AC) power supplied by an inverter.
  • Such motors may include two inverters, where each inverter is paired with one of the stators to individually provide power to the stator.
  • the motor When the rotation of the brushless motor is locked, that is, prevented from rotating, the motor may continue to receive current at peak or near-peak values from the inverters. As such, motor control when a motor is locked is subject to improvement.
  • the present disclosure describes a three-phase synchronous motor control technique and controller that may restrict an amount of the electric current supplied to the stator coils of an electric motor when the motor is in a locked state by superposing a compensation current to lower the peak values of currents supplied to the stator coils.
  • FIG. 1 illustrates a schematic diagram of a motor drive system in a first embodiment of the present disclosure
  • FIG. 2 illustrates a schematic diagram of a motor device in the first embodiment of the present disclosure
  • FIG. 3 illustrates a positional relationship between two stators and a rotor of the motor device in the first embodiment of the present disclosure:
  • FIG. 4A illustrates a coil position arrangement in one of the two stators of the motor device as viewed from the direction of arrow A shown in FIG. 3 ;
  • FIG. 4B illustrates a coil position arrangement in another of the two stators of the motor device as viewed from the direction of arrow A shown in FIG. 3 ;
  • FIG. 5 illustrates a waveform of a first three-phase base current
  • FIG. 6 illustrates a waveform of the first three-phase base current changing when the motor is locked:
  • FIG. 7 is a flowchart of a motor control process in the first embodiment of the present disclosure:
  • FIG. 8A illustrates a waveform of a current to be supplied to a U phase coil in a first stator of the motor device in the first embodiment of the present disclosure:
  • FIG. 8B illustrates a waveform of a current to be supplied to a V phase coil in the first stator of the motor device in the first embodiment of the present disclosure
  • FIG. 8C illustrates a waveform of a current to be supplied to a W phase coil in the first stator of the motor device in the first embodiment of the present disclosure
  • FIG. 8D illustrates a waveform of a current to be supplied to a U phase coil in a second stator of the motor device in the first embodiment of the present disclosure
  • FIG. 8E illustrates a waveform of a current to be supplied to a V phase coil in the second stator of the motor device in the first embodiment of the present disclosure
  • FIG. 8F illustrates a waveform of a current to be supplied to a W phase coil in the second stator of the motor device in the first embodiment of the present disclosure:
  • FIG. 9A illustrates waveforms of first three-phase currents supplied to the motor device on which a compensation current is superposed in the first embodiment of the present disclosure
  • FIG. 9B illustrates waveforms of second three-phase currents supplied to the motor device on which the compensation current is superposed in the first embodiment of the present disclosure
  • FIG. 10A illustrates a coil position arrangement in one of the two stators of the motor device as viewed from the direction of arrow A shown in FIG. 3 in a second embodiment of the present disclosure
  • FIG. 10B illustrates a coil position arrangement in another of the two stators of the motor device as viewed from the direction of arrow A shown in FIG. 3 in the second embodiment of the present disclosure
  • FIG. 11A illustrates a waveform of a current to be supplied to a U phase coil in a first stator of the motor device in the second embodiment of the present disclosure:
  • FIG. 11B illustrates a waveform of a current to be supplied to a V phase coil in the first stator of the motor device in the second embodiment of the present disclosure
  • FIG. 11C illustrates a waveform of a current to be supplied to a W phase coil in the first stator of the motor device in the second embodiment of the present disclosure
  • FIG. 11D illustrates a waveform of a current to be supplied to a U phase coil in a second stator of the motor device in the second embodiment of the present disclosure
  • FIG. 11E illustrates a waveform of a current to be supplied to a V phase coil in the second stator of the motor device in the second embodiment of the present disclosure
  • FIG. 11F illustrates a waveform of a current to be supplied to a W phase coil in the second stator of the motor device in the second embodiment of the present disclosure
  • FIG. 12A illustrate waveforms of the first three-phase currents supplied to the motor device on which the compensation current is superposed in the second embodiment of the present disclosure:
  • FIG. 12B illustrate waveforms of the second three-phase currents supplied to the motor device on which the compensation current is superposed in the second embodiment of the present disclosure.
  • FIG. 13 illustrates a schematic diagram of the motor device in other embodiments of the present disclosure.
  • a motor drive system 1 in the present embodiment includes a motor 3 , a motor controller 5 , a battery 7 , a first inverter 10 , and a second inverter 20 .
  • the motor drive system 1 may be disposed, for example, in a vehicle such as an automobile.
  • the motor 3 may be used to generate a propulsion force to drive the vehicle. That is, a force generated by the motor 3 may be used for rotating drive wheels on the vehicle to drive and propel the vehicle.
  • the battery 7 is a power source for driving the motor 3 .
  • the battery 7 includes a secondary battery that may be repeatedly recharged, such as, for example, a nickel-hydride battery and a lithium-ion battery. A direct current electric power is output from the secondary battery.
  • the first inverter 10 and the second inverter 20 are connected to the battery 7 in parallel.
  • the electric power of the battery 7 is supplied to the first inverter 10 and to the second inverter 20 .
  • the motor 3 is provided with a first stator 31 , a second stator 32 , and a rotor 33 .
  • the rotor 33 may be, for example, a permanent-magnet type rotor.
  • the motor 3 in the present embodiment is an inner rotor type synchronous motor configured to rotate the rotor 33 by generating a rotating magnetic field from the two stators 31 and 32 .
  • the first stator 31 includes a U phase coil 31 a , a V phase coil 31 b , and a W phase coil 31 c , as shown in FIGS. 2 and 4A .
  • the impedance of each of these coils 31 a , 31 b , and 31 c is the same.
  • These three coils 31 a , 31 b , and 31 c in the first stator 31 are configured as a wye (“Y”) connection where each of the coils 31 a , 31 b , and 31 c is connected to a common neutral point 31 d , as shown in FIG. 2 .
  • Y wye
  • the U phase coil 31 a , the V phase coil 31 b , and the W phase coil 31 c in the first stator 31 are arranged to be offset from one another at intervals of a preset angle (e.g., at 60-degree intervals) along the rotation direction of the rotor 33 .
  • one end of each of the three-phase coils 31 a , 31 b , 31 c is connected to the first inverter 10 while the other end of each of the three-phase coils 31 a , 31 b , and 31 c is connected to the neutral point 31 d.
  • the second stator 32 includes a U phase coil 32 a , a V phase coil 32 b , and a W phase coil 32 c , as shown in FIGS. 2 and 4B .
  • the impedance of each of these coils 32 a , 32 b , and 32 c is the same.
  • the impedance of the three coils 31 a , 31 b , and 31 c in the first stator 31 may be the same as the impedance of the three coils 32 a . 32 b , and 32 c in the second stator 32 , but the impedances may also be different.
  • These three coils 32 a , 32 b , and 32 c in the second stator 32 are configured as a wye (“Y”) connection where each of the coils 32 a , 32 b , and 32 c is connected to a common neutral point 32 d , as shown in FIG. 2 .
  • the U phase coil 32 a , the V phase coil 32 b , and the W phase coil 32 c in the second stator 32 are arranged to be offset from one another at intervals of a preset angle (e.g., at 60-degree intervals) along the rotation direction of the rotor 33 .
  • each of the three-phase coils 32 a . 32 b , 32 c is connected to the second inverter 20 while the other end of each of the three-phase coils 32 a , 32 b , and 32 c is connected to the neutral point 32 d.
  • the neutral point 31 d of the first stator 31 and the neutral point 32 d of the second stator 32 are electrically connected, as shown in FIG. 2 .
  • an arrangement position of the first stator 31 may refer to the position of each of the coils 31 a , 31 b , and 31 c in the first stator 31 relative to the rotor 33 in or along the rotation direction of the rotor 33 .
  • an arrangement position of the second stator 32 may refer to the position of each of the coils 32 a , 32 b , and 32 c in the second stator 32 relative to the rotor 33 in or along the rotation direction of the rotor 33 .
  • the U phase, V phase, and W phase in the first inverter 10 and in the first stator 31 may be respectively designated as the U 1 phase, V 1 phase, and W 1 phase, or some variation thereof
  • the U phase, V phase, and W phase in the second inverter 20 and in the second stator 32 may be respectively designated as the U 2 phase, V 2 phase, and W 2 phase, or some variation thereof.
  • the arrangement position of the first stator 31 and the arrangement position of the second stator 32 are different. More practically, the arrangement position of the second stator 32 is rotationally offset from the arrangement position of the first stator 31 by a specific angle (i.e., degrees) in the rotation direction of the rotor 33 . In this embodiment, the specific rotational offset is 180 degrees, as shown in FIGS. 4A and 4B . That is, the arrangement positions of the coils 32 a , 32 b , and 32 c in the second stator 32 are rotated 180 degrees from the arrangement positions of the coils 31 a , 31 b , and 31 c in the first stator 31 .
  • the positional offset between the stators 31 and 32 is described in greater detail below.
  • a resolver 4 is disposed in the motor 3 .
  • the resolver 4 is a sensor that detects a rotation angle of the rotor 33 in the motor 3 .
  • the resolver 4 outputs rotation angle information to the motor controller 5 based on the rotation angle of the rotor 33 , and the motor controller 5 detects the rotation angle of the rotor 33 based on the rotation angle information input from the resolver 4 .
  • the resolver 4 and the motor controller 5 can detect the rotation or rotational angle of the motor 3 by detecting the rotation angle of the rotor 33 .
  • the first three-phase currents Iu 1 , Iv 1 , Iw 1 are supplied respectively to the U phase coil 31 a , the V phase coil 31 b , and the W phase coil 31 c in the first stator 31 from the first inverter 10 .
  • the first three-phase currents may mean a first set of three currents Iu 1 , Iv 1 , and Iw 1 , with one of the three currents corresponding to each of the U 1 , V 1 , and W 1 phases or rather the coils 31 a , 31 b , and 31 c in the first stator.
  • the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o are computed for rotating the rotor 33 based on the rotation position of the rotor 33 .
  • the first three-phase base currents may mean a first set of three base currents with one base current corresponding to each of the U 1 , V 1 , and W 1 phases.
  • Iu 1 o is the base current of the U 1 phase
  • Iv 1 o is the base current of the V 1 phase
  • Iw 1 o is the base current of the W 1 phase.
  • the rotation position of the rotor 33 is detected as angle information in the motor controller 5 .
  • the rotation position of the rotor 33 may be designated as a rotation angle.
  • Each of the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o is a sine wave AC current having a predetermined frequency, as illustrated in FIG. 5 .
  • the V 1 base current Iv 1 o is shifted 120-degrees relative to the U 1 base current Iu 1 o , as shown in FIG. 5 .
  • the phase order may be U 1 , V 1 , and W 1 .
  • first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o may be supplied respectively to the phase coils 31 a , 31 b , and 31 c in the first stator 31 as the first three-phase currents Iu 1 , Iv 1 , Iw 1 .
  • the second three-phase currents Iu 2 , Iv 2 , Iw 2 are supplied to the U phase coil 32 a , the V phase coil 32 b , and the W phase coil 32 c in the second stator 32 from the second inverter 20 .
  • the second three-phase currents Iu 2 , Iv 2 , and Iw 2 may mean a second set of three currents, with one of the three currents corresponding to each of the U 2 , V 2 , and W 2 phases, or rather the coils 32 a . 32 b , and 32 c , in the second stator 32 .
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o are computed for rotating the rotor 33 based on the rotation position of the rotor 33 .
  • the second three-phase base currents may mean a second set of three base currents with one base current corresponding to each of the U 2 , V 2 , and W 2 phases.
  • Iu 2 o is the base current of the U 2 phase
  • Iv 2 o is the base current of the V 2 phase
  • Iw 2 o is the base current of the W 2 phase.
  • Each of the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o is a sine wave-shaped AC current having a predetermined frequency.
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o may have the same amplitude and the same frequency as the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o .
  • the second three-phase base currents for U 2 , V 2 , and W 2 may have a 120-degree phase shift between the base currents.
  • U 2 may be offset from V 2 and W 2 by 120-degrees.
  • These second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o may be supplied respectively to the phase coils 32 a , 32 b , and 32 c in the second stator 32 as the second three-phase currents Iu 2 , Iv 2 , Iw 2 respectively.
  • the first three-phase currents Iu 1 , Iv 1 , and Iw 1 supplied to the first inverter may be modifications or compensated values of the respective first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o .
  • the first-three phase currents Iu 1 , Iv 1 , and Iw 1 may be realized by superposing a first compensation current Io on the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o in the first inverter 10 , and then supplying these compensated base currents as the first three-phase currents Iu 1 , Iv 1 , and Iw 1 to the phase coils 31 a .
  • the currents supplied to the phase coils 31 a , 31 b , and 31 c may be referred to simply as the first three-phase current Iu 1 , Iv 1 , and Iw 1 , regardless of whether the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o are modified by the first compensation current Io.
  • the first three-phase base current Iu 1 o , Iv 1 o , and Iw 1 o may be supplied, as is (e.g., without compensation), as the first three-phase current Iu 1 , Iv 1 , and Iw 1 .
  • the principle of wave superposition may be used to combine two different waveforms and their representative values to represent a resultant wave.
  • the waveform of the first compensation current Io may be “superposed” on the first three-phase base current waveforms Iu 1 o , Iv 1 o , and Iw 1 o to realize the first three-phase currents Iu 1 , Iv 1 , and Iw 1 .
  • the superposition or combination of the waves and values assumes a phase matching (e.g., at the same phase angles) of the waves.
  • a phase matching e.g., at the same phase angles
  • the first compensation current Io when the first compensation current Io is superposed on the first three-phase base currents, the value of the first compensation current Io at a given phase angle is superposed onto the value of the first three-phase base currents at the same given phase angle.
  • the first compensation current Io has the same phase when it is superposed on the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o.
  • One purpose of superposing the first compensation current Io is to reduce and lower the peak value of the first three-phase currents Iu 1 , Iv 1 , Iw 1 supplied from the first inverter 10 to the first stator 31 to be less than the peak value of the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o . While the principle of wave superposition may be considered as an additive concept, the principle is not limited to an additive property in this description.
  • the superposing of the first compensation current Io on the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o may mean “subtracting” the values of the first compensation current Io from the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o.
  • the V 1 phase base current Iv 1 o when the rotation angle of the motor 3 is about 200 degrees, the V 1 phase base current Iv 1 o is close to reaching a peak value. As shown in FIG. 6 , if the motor 3 locks at such time (i.e., the time when the motor lock condition occurs or “lock generation timing”), the V 1 phase base current Iv to will maintain a high value at or near the peak current value. As such, the circuit and/or individual circuit elements in which the V 1 phase base current Iv 1 o flows may be affected and/or damaged by such a high amount of current.
  • the predetermined current compensation conditions are satisfied, and a peak current or a near-peak current is prevented from continuously flowing to the first stator 31 by superposing the first compensation current Io on the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o .
  • the predetermined current compensation condition may be the locking of the motor 3 , which triggers the superposing of the first compensation current Io on the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o to realize and supply the first three-phase currents Iu 1 , Iv 1 , and Iw 1 to the coils of the first stator 31 .
  • each of the first three compensation currents Io are combined at the neutral point 31 d of the first stator 31 , and flows from the neutral point 31 d on the first stator to the neutral point 32 d of the second stator 32 after such combination.
  • the combined compensation currents are divided to respectively flow to each of the phase coils 32 a , 32 b , and 32 c of the second stator 32 , and are then input to the second inverter 20 through each of the phase coils 32 a , 32 b , and 32 c.
  • the first compensation current Io in each phase flows through the current path that extends from the first inverter 10 through the first stator 31 and further through the second stator 32 to the second inverter 20 .
  • a second compensation current ⁇ Io that has the same phase but a reverse polarity of the first compensation current Io is supplied from the second inverter 20 to each of the phase coils 32 a , 32 b , and 32 c of the second stator 32 .
  • the second compensation currents ⁇ Io supplied to the phase coils 32 a , 32 b , and 32 c have the same phase as each other.
  • the description refers to the first compensation current Io in the positive and the second compensation current ⁇ Io in the negative, but due to the cyclical nature of the current waveforms, the respective compensation currents are not limited to these polarity designations. For example, there may be times when the first compensation current Io is a negative value and during these times, the second compensation current ⁇ Io may be a positive value.
  • the second three-phase base currents Iu 2 o . Iv 2 o , and Iw 2 o may have, respectively, the second compensation current ⁇ Io superposed thereon to become the second three-phase currents Iu 2 , Iv 2 , Iw 2 that are supplied to the phase coils 32 a . 32 b , and 32 c.
  • the supply of the second compensation current ⁇ Io to each of the phase coils 32 a , 32 b , and 32 c of the second stator 32 means that the first compensation current Io is supplied to each of the phase coils 32 a , 32 b , and 32 c of the second stator 32 in a reverse direction.
  • the polarity of the first compensation current Io supplied to the phase coils 32 a , 32 b , and 32 c of the second stator 32 is reversed relative to the flow direction of the first compensation current Io when it is supplied to the first stator 31 .
  • the first compensation current Io may be considered as forming a power supply loop, which extends from a positive terminal of the battery 7 to the first inverter 10 , through the first/second stators 31 , 32 to the second inverter 20 , and back to a negative terminal of the battery 7 .
  • the first compensation current Io may be supplied from the first inverter 10 and the second compensation current ⁇ Io may be supplied from the second inverter 20 to suppress the peak value of the first three-phase current Iu 1 , Iv 1 , and Iw 1 to a lower value.
  • the size (i.e., amount) of the second compensation current ⁇ Io relative to the second three-phase base currents Iu 2 o . Iv 2 o , and Iw 2 o it is possible that the peak value of the second three-phase currents Iu 2 , Iv 2 , and Iw 2 may be larger than the peak value of the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o.
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o are supplied to the second stator 32 having a different phase. That is, the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o may have a different phase (e.g., offset) from the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o .
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o may have a 180-degree phase shift from the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o.
  • the arrangement position of the second stator 32 may also be rotationally shifted in the rotation direction of the rotor 33 by a specific degree or rotational angle relative to the arrangement position of the first stator 31 , for example, as shown in FIGS. 4A and 4B .
  • the arrangement position of the second stator 32 is rotated 180 degrees relative to the arrangement position of the first stator 31 .
  • Such a rotation of the second stator 32 when the three-phase base currents Iu 2 o . Iv 2 o , and Iw 2 o are phase shifted may limit the reduction of the output torque from the second stator 32 .
  • the first inverter 10 is provided with a three-phase bridge circuit 11 including six switching elements Tr 1 , Tr 2 , Tr 3 , Tr 4 , Tr 5 , and Tr 6 .
  • Each of the switching elements Tr 1 -Tr 6 may be an insulated-gate type bipolar transistor in the present embodiment.
  • the positive terminal and the negative terminal of the battery 7 are connected to the three-phase bridge circuit 11 to supply a direct current (DC) power to the bridge circuit 11 .
  • a first driving signal for driving the first inverter 10 is provided from the motor controller 5 to the first inverter 10 .
  • the switching elements Tr 1 -Tr 6 are turned on or off based on the first driving signal.
  • the first inverter 10 converts the DC electric power supplied from the battery 7 into the three-phase currents, and supplies the three-phase currents to the first stator 31 .
  • the inverter 10 takes the DC input from the battery 7 and provides an AC output for the first stator 31 .
  • the three-phase currents provided to the stator 31 are used to generate a magnetic field to rotate the rotor 33 of the motor 3 .
  • the first inverter 10 converts the direct current electric power supplied from the battery 7 to the first three-phase currents that have a U 1 phase current Iu 1 , a V 1 phase current Iv 1 , and a W 1 phase current Iw 1 based on the driving signal from the motor controller 5 . Then, the U 1 phase current Iu 1 is supplied to the U phase coil 31 a , the V 1 phase current Iv 1 is supplied to the V phase coil 31 b , and the W 1 phase current Iw 1 is supplied to the W phase coil 31 c.
  • the first three-phase currents Iu 1 , Iv 1 , Iw 1 are the first three-phase base currents Iu 1 o . Iv 1 o , and Iw 1 o . That is, the first-three phase current Iu 1 , Iv 1 , and Iw 1 may be based on the rotation angle of the rotor 33 relative to the first stator 31 , such that the U 1 phase uses the base current Iu 1 o , the V 1 phase uses the base current Iv 1 o , and the W 1 phase uses the base current Iw 1 o.
  • the first inverter 10 supplies each of the phase coils 31 a , 31 b , and 31 c with the respective first three-phase currents Iu 1 , Iv 1 , and Iw 1 , which are realized as the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o with the superposed compensation current Io.
  • the first inverter 10 supplies each of the phase coils 31 a , 31 b , and 31 c based on the first driving signal from the motor controller 5 upon satisfaction of the current compensation conditions.
  • the first inverter 10 includes an input capacitor 12 and a voltage sensor 13 .
  • the input capacitor 12 and the voltage sensor 13 are respectively connected in parallel with the three-phase bridge circuit 11 to the battery 7 .
  • the voltage sensor 13 detects the voltage of the battery power that is input from the battery 7 to the first inverter 10 and outputs a detection signal based on the detected voltage to the motor controller 5 .
  • the first inverter 10 also includes two current sensors 16 and 17 .
  • the current sensor 16 is disposed on the V 1 phase current path by which the current Iv 1 is supplied from the three-phase bridge circuit 11 to the motor 3 .
  • the current sensor 16 detects the V 1 phase current Iv 1 and outputs a detection signal with the value of the V 1 phase current Iv 1 to the controller 5 .
  • the current sensor 17 is disposed on the W 1 phase current path and detects the W 1 phase current Iw 1 supplied from the three-phase bridge circuit 11 to the motor 3 .
  • the current sensor 17 outputs a detection signal with the value of the W 1 phase current to the motor controller 5 .
  • the motor controller 5 can determine a value of each of the first three-phase currents Iu 1 , Iv 1 , Iw 1 .
  • the second inverter 20 is configured in much the same way as the first inverter 10 . That is, the second inverter 20 converts the direct current electric power supplied from the battery 7 to the three-phase currents based on a second driving signal from the motor controller 5 for driving the second inverter 20 , and supplies the three-phase currents to the second stator 32 .
  • the second stator 32 uses the three-phase currents to rotate the rotor 33 of the motor 3 .
  • the second inverter 20 converts the direct current electric power supplied from the battery 7 to the second three-phase currents that have a U 2 phase current Iu 2 , a V 2 phase current Iv 2 , and a W 2 phase current Iw 2 based on the second driving signal from the motor controller 5 . Then, the U 2 phase current Iu 2 is supplied to the U phase coil 32 a , the V 2 phase current 1 v 2 is supplied to the V phase coil 32 b , and the W 2 phase current Iw 2 is supplied to the W phase coil 32 c.
  • the second three-phase currents Iu 2 , Iv 2 , Iw 2 are the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o . That is, the U 2 phase uses the base current Iu 2 o , the V 2 phase uses the base current Iv 2 o , and the W 2 phase uses the base current Iw 2 o.
  • the second inverter 20 when the current compensation conditions are satisfied, the second inverter 20 superposes the second compensation current ⁇ Io on each of the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o , and supplies the compensated three-phase base currents to the respective phase coils 32 a , 32 b , and 32 c , based on the output of the second driving signal from the motor controller 5 when the current compensation conditions are satisfied.
  • the motor controller 5 controls the drive of the motor 3 by controlling the first inverter 10 and the second inverter 20 based on various signals and information, including input signals from the resolver 4 , each of the current sensors 16 and 17 , and the voltage sensor 13 .
  • the control of the first inverter 10 by the motor controller 5 may be designated simply as a “first drive control”
  • the control of the second inverter 20 by the motor controller 5 may be designated simply as a “second drive control.”
  • the motor controller 5 includes a control section 5 a and a storage section 5 b .
  • the control section 5 a has a CPU or like processor.
  • the storage section 5 b has a semiconductor memory that may be, for example, a ROM, a RAM, an NVRAM, and a flash memory. That is, the motor controller 5 in the present embodiment may be a microcomputer including a CPU and a semiconductor memory.
  • the control section 5 a may include a first calculator 5 al , a second calculator 5 a 2 , a first drive controller 5 a 3 , a second drive controller 5 a 4 , a compensation current calculator 5 a 5 , and a compensation condition determiner 5 a 6 .
  • the control section 5 a may refer either to a microcomputer or like processing device, or to the elements 5 al - 5 a 6 collectively.
  • the control section 5 a may realize various functions including the first drive control and the second drive control by executing a program or instruction set stored in the storage section 5 b .
  • the storage section 5 b may be a non-transitive, substantive storage medium that stores a program or instruction set.
  • Various kinds of programs and data, including a program for a current compensation and a current control process may be stored in the storage section 5 b.
  • control section 5 a may not be limited to realization by an execution of a program by a microcomputer 5 a , but may also be realized by dedicated or specific hardware.
  • the various functions realized by the control section 5 a are realized by a microcomputer 5 a executing a program or instruction set stored in the storage section 5 b
  • the first calculator 5 al , the second calculator 5 a 2 , the first drive controller 5 a 3 , the second drive controller 5 a 4 , the compensation current calculator 5 a 5 , and the compensation condition determiner 5 a 6 may be considered as functional blocks, e.g., processes performed by the microcomputer 5 a of the motor controller 5 , as described below in greater detail with reference to FIG. 7 .
  • each of the first calculator 5 al , the second calculator 5 a 2 , the first drive controller 5 a 3 , the second drive controller 5 a 4 , the compensation current calculator 5 a 5 , and the compensation condition determiner 5 a 6 may each be hardware components or a combination of a plurality of hardware components (e.g., circuits).
  • the first calculator 5 al , the second calculator 5 a 2 , the first drive controller 5 a 3 , the second drive controller 5 a 4 , the compensation current calculator 5 a 5 , and the compensation condition determiner 5 a 6 may be realized as digital circuits with digital components, analog circuits with analog components, or a combination of both, in addition to having logical circuit elements such as logic gates, latches, and the like.
  • Each of the first calculator 5 al , the second calculator 5 a 2 , the first drive controller 5 a 3 , the second drive controller 5 a 4 , the compensation current calculator 5 a 5 , and the compensation condition determiner 5 a 6 may be realized as an application-specific integrated circuit (ASIC), field-programmable gate array, or like specialized hardware circuit configured to perform a specific process.
  • ASIC application-specific integrated circuit
  • the specific processes performed by the first calculator 5 al , the second calculator 5 a 2 , the first drive controller 5 a 3 , the second drive controller 5 a 4 , the compensation current calculator 5 a 5 , and the compensation condition determiner 5 a 6 are described in greater detail below with reference to FIG. 7 .
  • the motor controller 5 performs the first drive control for generating a maximum torque on the rotor 33 based on the rotation angle of the rotor 33 . That is, the motor controller 5 computes the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o having a phase based on the rotation angle of the rotor 33 relative to the first stator 31 , for rotating the rotor 33 .
  • the relations between the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o , the phase current values of the base currents, and the rotation angles of the rotor 33 are illustrated in FIG. 5 .
  • the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o are computed for generating the maximum torque on the rotor 33 , for example, as shown in FIG. 5 .
  • the first driving signal is output to the first inverter 10 , for supplying the computed first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o to the first stator 31 as the first three-phase currents Iu 1 , Iv 1 , Iw 1 .
  • the first compensation current Io is computed. Then, the first driving signal is output to the first inverter 10 to supply the first three-phase currents Iu 1 , Iv 1 , Iw 1 to the first stator 31 .
  • the first three-phase currents Iu 1 , Iv 1 , and Iw 1 are realized as the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o with the superposed first compensation current Io.
  • the first compensation current Io is computed, for example, based on the first three-phase base currents.
  • the motor controller 5 performs the second drive control for generating a maximum torque on the rotor 33 based on the rotation angle of the rotor 33 . That is, the motor controller 5 computes the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o having a phase based on the rotation angle of the rotor 33 relative to the second stator 32 , for rotating the rotor 33 . That is, motor controller 5 computes the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o that are capable of generating the maximum torque on the rotor 33 .
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o are computed as respectively having a 180-degree phase shift from the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o , since the arrangement position of the second stator 32 has a phase shift of 180 degrees relative to the arrangement position of the first stator 31 .
  • the second driving signal is output to the second stator 32 for supplying the computed second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o as the second three-phase currents Iu 2 , Iv 2 , Iw 2 to the second inverter 20 .
  • the second compensation current ⁇ Io is computed. Then, the second driving signal is output to the second inverter 20 for supplying the second three-phase currents Iu 2 , Iv 2 , and Iw 2 to the second stator 32 that respectively have the computed second compensation current ⁇ Io superposed on the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o.
  • the motor control process performed by the motor controller 5 is described with reference to FIG. 7 .
  • the following description of the motor control process performed by the motor controller 5 realizes both the process where the control section 5 a executes a program or instruction set saved in the storage section 5 b for performing the following processes, or where the motor controller 5 includes hardware components such as the first calculator 5 a 1 , the second calculator 5 a 2 , the first drive controller 5 a 3 , the second drive controller 5 a 4 , the compensation current calculator 5 a 5 , and the compensation condition determiner 5 a 6 for performing the processes described below.
  • Motor controller 5 may be used to generally describe the structural element performing the processes below, but this may mean, more specifically, processes performed by either the control section 5 a realized as a microcomputer or other processing device, or by the individual hardware components 5 al - 5 a 6 .
  • the control section 5 a will carry out a repeated execution of the motor control process of FIG. 7 at a predetermined interval (e.g., at every 100 microseconds) when a drive condition is satisfied for driving the motor 3 to generate a torque, that is, when the motor is to be driven/operated.
  • a predetermined interval e.g., at every 100 microseconds
  • the control section 5 a computes instruction values that respectively indicate (i) the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o , and (ii) the second three-phase base currents Iu 2 o . Iv 2 o , and Iw 2 o , based on the rotation angle of the rotor 33 as detected by the resolver 4 .
  • the first calculator 5 al may compute the instruction values for the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o based on the rotation angle of the rotor 33
  • the second calculator 5 a 2 may calculate the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o based on the rotation angle of the rotor 33 .
  • the motor controller 5 calculates a U 1 phase base current instruction value indicating the U 1 phase base current Iu 1 o , a V 1 phase base current instruction value indicating the V 1 phase base current Iv 1 o , a W 1 phase base current instruction value indicating the W 1 phase base current Iw 1 o , a U 2 phase base current instruction value indicating the U 2 phase base current Iu 2 o , a V 2 phase base current instruction value indicating the V 2 phase base current Iv 2 o , and a W 2 phase base current instruction value indicating the W 2 phase base current Iw 2 o . More specifically, the control section 5 a or the first calculator 5 a 1 and the second calculator 5 a 2 may computer these instruction values.
  • the motor controller 5 determiners whether the current compensation conditions are satisfied.
  • the microcomputer 5 a or the compensation condition determiner 5 a 6 may be used to determine whether the current compensation conditions are satisfied.
  • the current compensation conditions may include, for example, conditions where the motor 3 is locked, that is, conditions where the motor 3 is in a locked condition or locked state.
  • the motor 3 may be in a lock state (i) when the rotor 33 of the motor 3 completely stops, (ii) when the rotation speed of the rotor 33 is equal to or below a predetermined threshold, or (iii) when the rotation speed of the rotor 33 continues to be equal to or below a predetermined threshold for a predetermined duration or longer.
  • Various detection methods may be used to determine whether the motor 3 is in a lock state or lock condition.
  • the lock state may be detected based on the current values detected by each of the current sensors 16 and 17 .
  • the lock state may also be detected based on the rotation angle of the rotor 33 detected by the resolver 4 .
  • Other specialized hardware for detecting a lock condition of the motor 3 may be used, with such hardware outputting a signal indicative of a motor lock condition to the motor controller 5 .
  • specialized hardware for determining the rotation speed of the rotor and/or a timing circuit may be used to determine whether the motor 3 is in a locked state or condition.
  • the output of such sensors and hardware may be input to the microcomputer 5 a or the compensation condition determiner 5 a 6 to determine whether the current compensation conditions are satisfied.
  • the process proceeds to S 130 and the motor controller 5 (e.g., control section 5 a or compensation current calculator 5 a 5 ) sets both of the first compensation current value and the second compensation current value to 0, and the process proceeds to S 170 .
  • the motor controller 5 may also calculate a first compensation current instruction value and a second compensation current instruction value respectively corresponding to the compensation current values of 0. Each of the first compensation current instruction value and the second compensation current instruction value may also have values of 0.
  • the motor controller 5 obtains a maximum current value from among the first three-phase currents Iu 1 , Iv 1 , and Iw 1 currently being supplied to the first stator 31 .
  • the motor controller 5 may obtain the maximum current value, for example, based on each of the detection signals from the current sensors 16 and 17 .
  • the motor controller 5 may obtain the maximum value of the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o computed at S 110 .
  • the motor controller 5 obtains a minimum current value from among the first three-phase currents Iu 1 , Iv 1 , and Iw 1 currently being supplied to the first stator 31 .
  • the minimum current value may be, for example, obtained based on each of the detection signals from the current sensors 16 and 17 .
  • the motor controller 5 may obtain a minimum value of the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o computed at S 110 .
  • the motor controller 5 computes the first compensation current value (Io) and the second compensation current value ( ⁇ Io). More practically, the motor controller may calculate an average of the maximum current value obtained at S 140 and the minimum current value obtained at S 150 and set the average as the first compensation current value. The controller may set the additive inverse of the first compensation current value, that is, the opposite or negation of the first compensation current value, as the second compensation current value. For example, if the first compensation current value is 1, the motor controller 5 may set the second compensation current value to ⁇ 1. As another example, if the first compensation current value is ⁇ 3, the motor controller 5 may set the second compensation current value to 3.
  • the motor controller 5 calculates the first compensation current instruction value corresponding to the first compensation current value and calculates the second compensation current instruction value corresponding to the second compensation current value.
  • the compensation currents may appear as triangle waves, and as third harmonics of the three-phase base currents. That is, the compensation currents may be three times the frequency of the three-phase base currents.
  • the motor controller 5 that is either the control section 5 a realized as a microcomputer or the first drive controller 5 a 3 , computes the instruction value indicating each of the first three-phase currents Iu 1 , Iv 1 , Iw 1 that are to be supplied to the first stator 31 , that is, a U 1 phase current instruction value, a V 1 phase current instruction value, and a W 1 phase current instruction value. More practically, the motor controller 5 computes the U 1 phase current instruction value by subtracting the first compensation current instruction value computed at S 130 or S 160 from the U 1 phase base current instruction value computed at S 110 . That is, the first compensation current instruction value is superposed on the U 1 phase base current instruction value.
  • the U 1 phase current instruction value is set to be equal to the U 1 phase base current instruction value, which means that the first compensation current value is not superposed.
  • the first compensation current instruction value is a value computed at S 160 , that is, when the current compensation conditions are satisfied
  • the U 1 phase current instruction value is a value different from the U 1 phase base current instruction value. That is, the U 1 phase current instruction value is set as an instruction value computed from the superposition of the first compensation current value on the U 1 phase base current value.
  • the V 1 phase current instruction value is computed by subtracting the first compensation current instruction value computed at S 130 or S 160 from the V 1 phase base current instruction value computed at S 110 .
  • the W 1 phase current instruction value is computed by subtracting the first compensation current instruction value computed at S 130 or S 160 from the W 1 phase base current instruction value.
  • the motor controller 5 more specifically either the control section 5 a realized as a microcomputer or the second drive controller 5 a 4 , computes the instruction value indicating each of the second three-phase currents Iu 2 , 1 v 2 , and Iw 2 that are to be supplied to the second stator 32 , that is, the U 2 phase current instruction value, the V 2 phase current instruction value, and the W 2 phase current instruction value.
  • the computation method for these instruction values is the same as the computation method used at S 170 .
  • the U 2 phase current instruction value is computed by subtracting the second compensation current instruction value computed at S 130 or S 160 from the U 2 phase base current instruction value computed at S 110 . That is, the U 2 phase current instruction value is computed by superposing the second compensation current instruction value with the U 2 phase base current instruction value.
  • the U 2 phase current instruction value is set to be equal to the U 2 phase base current instruction value, which means that there is no superposing or combining of the U 2 phase base current instruction value and the second compensation current value.
  • the second compensation current instruction value is a value computed at S 160
  • the U 2 phase current instruction value is different from the U 2 phase base current instruction value. That is, the U 2 phase current instruction value is set as an instruction value realized by superposing or combining the second compensation current value with the U 2 phase base current value.
  • the V 2 phase current instruction value is computed by subtracting the second compensation current instruction value computed at S 130 or S 160 from the V 2 phase base current instruction value computed at S 110 .
  • the W 2 phase current instruction value is computed by subtracting the second compensation current instruction value computed at S 130 or S 160 from the W 2 phase base current instruction value.
  • the motor controller 5 based on the U 1 phase current instruction value, the V 1 phase current instruction value, and the W 1 phase current instruction value computed at S 170 , the motor controller 5 , specifically either the control section 5 a realized as a microcomputer or the first drive controller 5 a 3 , generates the first driving signal for driving the first inverter 10 and outputs the first driving signal to the first inverter 10 .
  • the first three-phase currents Iu 1 . Iv 1 , and Iw 1 are supplied from the first inverter 10 to the first stator 31 based on each of the instruction values.
  • the motor controller 5 also generates the second driving signal for driving the second inverter 20 and outputs the second driving signal to the second inverter 20 at S 190 based on the U 2 phase current instruction value, the V 2 phase current instruction value, and the W 2 phase current instruction value computed at S 180 .
  • the second three-phase currents Iu 2 , Iv 2 , and Iw 2 are supplied from the second inverter 20 to the second stator 32 based on each of the instruction values.
  • the waveforms of the electric currents to be supplied to each of the coils in the stators 31 , 32 are shown respectively in FIGS. 8A-8F . That is, for each of the coils (i.e., for each of the phases U, V, and W), the base current waveforms before the superposition of the compensation current are shown respectively in FIGS. 8A-8F together with the compensation current and the supplied electric current waveforms, where the supplied electric current waveform is the base current waveform with the compensation current waveform subtracted therefrom (e.g., superposed thereon).
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o have the same frequency as the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o , with the phase of each current shifted by 180 degrees from the phase of each of the first three-phase base currents.
  • the phase shift of 180 degrees is caused by a shift of the arrangement position of the second stator 32 relative to the arrangement position of the first stator 31 by a certain mechanical angle that corresponds to a 180-degree electrical angle. In the present embodiment, the shift of the mechanical angle is 180 degrees.
  • the second compensation current ⁇ Io has the same phase as the first compensation current Io, but with a reversed polarity. That is, the waveform of the second compensation current ⁇ Io is a flipped waveform of the first compensation current Io.
  • Each compensation current has a triangular waveform and is the third harmonic (i.e., third-order harmonic frequency) of the base frequency.
  • the U 1 phase base current Iu 1 o takes a peak value.
  • the peak value of the base current Iu 1 o when the motor 3 is at a rotation angle of 150 degrees is about ⁇ 100 A.
  • the first compensation current is superposed on (e.g., subtracted from) the U 1 phase base current Iu 1 o , such a peak value of the U 1 phase base current Iu 1 o is lowered. That is, the peak value of the U 1 phase current Iu 1 is lowered to be less than the peak value of the U 1 phase base current Iu 1 o .
  • the value of the first compensation current is about ⁇ 25 A when the rotation angle of the motor 3 is at 150 degrees.
  • the peak value of the U 1 phase current Iu 1 is about ⁇ 75 A when the rotation angle of the motor is at 150 degrees.
  • the polarity of the second compensation current (e.g., ⁇ Io) is reversed relative to the first compensation current (e.g., Io) in terms of the +/ ⁇ sign.
  • the arrangement position of the second stator 32 is shifted by 180 degrees relative to the arrangement position of the first stator 31 , to have a phase shift of 180 degrees for the second three-phase base current relative to the phase of the first three-phase base current. Therefore, a peak value is lowered for both of the first three-phase base current and the second three-phase base current due to the superposition of the corresponding compensation current.
  • the peak value of the U 2 phase current Iu 2 is about 75 A when the rotation angle of the motor is at 150 degrees, due to the shift of the arrangement position of the second stator 32 , as described above.
  • FIGS. 9A and 9B show an extraction of the compensated phase current waveforms shown in FIGS. 8A-8F for each of the two inverters 10 and 20 . That is, when the superposition of the compensation current is performed, the three-phase current having a waveform shown in FIG. 9A is supplied from the inverter 10 to the stator 31 , and the three-phase current having a waveform shown in FIG. 9B is supplied from the inverter 20 to the stator 32 .
  • the torque generated by the rotor 33 based on the supply of the compensated first three-phase currents (i.e., from the compensated phase current waveform) to the first stator 31 is equal to the torque generated by the first three-phase base currents.
  • the torque generated by the rotor 33 using the compensated currents is equal to the torque generated by the first three-phase base currents without the compensation. Since the first compensation current having the same phase is subtracted from (i.e., superposed on) each of the three-phase base currents, there is no torque change due to the superposition of the first compensation current. Similarly, there is no torque change between the second three-phase currents on which the second compensation current is superposed. That is, the torque generated by the rotor 33 by receiving a supply of the second three-phase current to the second stator 32 is the same regardless of the superposition of the second compensation current.
  • the first stator 31 when the current compensation conditions are satisfied, receives a supply of the first three-phase currents Iu 1 , Iv 1 , Iw 1 that are the first-three phase base currents Iu 1 o , Iv 1 o , and Iw 1 o , where the first compensation current Io having the same phase has been subtracted (i.e., superposed on).
  • the second stator 32 receives a supply of the second three-phase currents 1 u 2 , Iv 2 , 1 w 2 that are the second-three phase base current Iu 2 o , Iv 2 o , and Iw 2 o , where the second compensation current ⁇ Io having the same phase has been subtracted (i.e., superposed on).
  • the second compensation current ⁇ Io is an electric current having the same phase as the first compensation current Io, but with a reversed polarity.
  • the motor drive system 1 of the present embodiment can lower the peak value of the first three-phase currents Iu 1 , Iv 1 , Iw 1 to be lower than the peak value of the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o where no first compensation current Io is superposed.
  • the motor drive system 1 can also control the peak value of the second three-phase currents Iu 2 , 1 v 2 , Iw 2 to be lower than the peak value of the second three-phase base current Iu 2 o . Iv 2 o , and Iw 2 o where no second compensation current ⁇ Io is superposed. Therefore, it is possible to control and restrict the current supplied to each of the phase coils of each of the stators 31 and 32 when the motor 3 locks, while continuing the supply of each of the three-phase currents, even when the motor 3 is in a lock state.
  • the maximum loss of the semiconductor switching elements used in each of the inverters 10 and 20 may be reduced, thereby improving the fuel consumption rate of the vehicle.
  • the volume and weight of the wiring that is used for supplying each of the three-phase currents from the inverters 10 and 20 to the stators 31 and 32 may also be reduced.
  • the arrangement position of each of the stators 31 and 32 is shifted by 180 degrees from each other, and the motor controller 5 generates the instruction values of the three-phase base currents to a provide maximum torque from each of the stators 31 and 32 to the rotor 33 according to the rotation angle of the rotor 33 .
  • the phase difference between the first and second three-phase base currents will also be 180 degrees.
  • the second compensation current ⁇ Io differs in the phase by 180 degrees relative to the first compensation current Io
  • the second three-phase base current also differs in the phase by 180 degrees relative to the first three-phase base current, a peak value is lowered by the corresponding compensation current for each of all three-phase currents.
  • Each compensation current is generated based on the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o . Therefore, each compensation current is easily and appropriately computable.
  • each of the compensation currents is computed as a triangular waveform current as a third harmonic frequency of the three-phase base current, where the frequency of the compensation current is three times the frequency of the three-phase base currents.
  • the compensation current is superposed.
  • the compensation current may be superposed when conditions for lowering the peak value, such as a motor lock state, are satisfied.
  • the compensation current when there is no need to superpose the compensation current, superposition of the compensation current will not be performed, thereby reducing the processing load for the superposition of the compensation current.
  • the current compensation conditions include a condition that the motor 3 is locked. Thereby, when the motor 3 locks, a large current close to the peak value of the three-phase base current is prevented from continuously flowing in any of the coils.
  • the arrangement position of the second stator 32 is shifted by 180 degrees relative to the first stator 31 .
  • the arrangement positions of the first stator 31 and the second stator 32 of the motor 3 in the second embodiment may be different.
  • the arrangement position of the second stator 32 is shifted by 60 degrees relative to the first stator 31 .
  • the motor controller 5 supplies each of the three-phase currents to the motor 3 in such configuration, by performing the motor control process shown in FIG. 7 .
  • Example waveforms of the electric currents in respective phases supplied to each of the coils in the stators 31 and 32 in the second embodiment are shown in FIGS. 11A-11F .
  • the phase is shifted 60 degrees relative to the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o .
  • the second three-phase base currents Iu 2 o , Iv 2 o , and Iw 2 o are out of phase by 60 degrees relative to the corresponding first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o , shown respectively in FIGS. 11A-11C .
  • the phase shift of 60 degrees originates in (i.e., is caused by) a shift of the 60-degree mechanical angle of the arrangement position of the second stator 32 relative to the arrangement position of the first stator 31 , corresponding to a shift of the 60-degree electrical angle.
  • a peak value is reduced in both of the first three-phase base currents and the second three-phase base currents by the superposition of the corresponding compensation currents.
  • FIGS. 12A and 12B are respectively an extraction of the waveform when the compensation current is superposed for the respective inverters, based on the waveform of each of the phases in FIGS. 11A-11F . That is, in the second embodiment, when superposition of the compensation current is performed, the three-phase currents having a waveform shown in FIGS. 12A and 12B are supplied from the inverters 10 and 20 to the stators 31 and 32 .
  • the torque generated by the rotor 33 according to the first three-phase currents on which the first compensation current is superposed is the same as the torque generated by the rotor 33 based on the first three-phase currents on which no first compensation current is superposed. The same applies to the torque generated by the rotor 33 based on the second three-phase currents on which the second compensation current is superposed.
  • the motor controller in such configuration in the second embodiment achieves the same effects as the first embodiment.
  • the compensation current may be computed by other methods. That is, the computation of the compensation current based on the maximum and the minimum of the first three-phase base currents Iu 1 o , Iv 1 o , and Iw 1 o in the first embodiment, for example, as described at S 140 -S 160 in FIG. 7 , and generation of the triangular waveform compensation current having a third-order harmonic frequency of the base current frequency, is a non-limiting example of such a computation method.
  • the waveform, the amplitude and, the frequency of the compensation current, as well as a relationship between the frequency of the compensation current and the phases of the three-phase base currents, may be changed and/or determined in different ways.
  • the frequency of the compensation current is not limited to the third-order harmonic frequency of the three-phase base currents, but may also be an n-th order harmonic where “n” is a natural number of 2 or more. That is, the compensation current may be a second harmonic or more of the three-phase base currents.
  • the compensation current may not necessarily be an electric current with a periodically-changing waveform.
  • the compensation current may be a DC current.
  • the compensation current may be an electric current which enables a reduction of the peak value of each of the three-phase currents to at least one of two inverters 31 and 32 , which is computable by various computation methods appropriate for such purposes.
  • phase difference or rather a “base current phase difference,” among the three-phase base currents and/or the amount of shift angle between the arrangement positions of the stators 31 and 32 , or rather a “stator angle shift amount,” is not necessarily limited to the amounts in the above-described embodiments.
  • the base current phase difference of 180 degrees and the stator angle shift amount of 180 degrees in the first embodiment as well as the base current phase difference of 60 degrees and the stator angle shift amount of 60 degrees in the second embodiment are respectively non-limiting examples.
  • At least one of the base current phase difference and the stator angle shift amount may be determined arbitrarily as long as at least one of them is capable of reducing the peak value of at least one of the three-phase currents supplied to the stators 31 and 32 when the superposition of the compensation current is performed.
  • each of the stators 31 and 32 and the stator angle shift amount may be arbitrarily determined as shown by the above example, i.e., the three-phase currents that are supplied from the stators 31 and 32 with the 180-degree base current phase difference are computable to enable a generation of the maximum torque by the rotor.
  • the arrangement of the coils in the stators 31 and 32 may be different from the arrangements shown in FIGS. 4A and 4B . That is, the coil arrangement configurations and the coil winding methods may generally vary in the stators of the synchronous motors, and the motor controller of the present disclosure is applicable to any of those variations of the stator configuration and to the configuration of the motor device.
  • the motor 3 which is described as a “two stators and one rotor” type motor, as an example of the motor device in the above-mentioned embodiments, may have a different configuration. That is, the motor device may have a configuration of at least two stators and with three coils in a wye configuration in each of the stators together with a neutral point connection between the two stators.
  • the rotor of the motor device may not be limited to a permanent-magnet type, but may also be other types.
  • FIG. 13 illustrates a motor device 70 configured as a combination of two motors 71 and 76 respectively having one stator and one rotor.
  • the motor 71 has one stator and one rotor (not illustrated), and the motor 76 also has one stator and one rotor (not illustrated), where the neutral points 31 d and 32 d of two stators 72 and 77 are electrically connected to each other.
  • Current compensation conditions may include other kinds of conditions.
  • the current compensation conditions may include at least one condition that does not involve a lock of the motor 3 .
  • the current compensation conditions may include at least one condition, in addition to a “motor 3 locked” condition.
  • satisfaction of the current compensation conditions may be determined as (i) a satisfaction of at least one of those conditions (e.g., the occurrence or fulfillment of at least one of the conditions), as (ii) a satisfaction of at least two conditions, or as (iii) a satisfaction of all conditions.
  • the compensation current may always be superposed on each of the three-phase base currents.
  • a so-called vector control operation method may be adopted as a control operation without computing the three-phase current instruction values, for generating the drive signal to the second inverter 20 .
  • a so-called vector control operation method may be adopted as a control operation without computing the three-phase current instruction values, for generating the drive signal to the second inverter 20 .
  • each of the second three-phase currents includes the second compensation current as a result.
  • the present disclosure may also be realized as a motor drive system using the motor controller described above as one of its components.
  • the present disclosure also contemplates the methods performed by the motor controller described above, as well as a non-transitive, substantive storage medium, such as a semiconductor memory, that stores a program or instruction set, that, when executed by a processor, causes the methods described above to be performed by the motor controller or other components, as well as other various modifications.

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